Arcograph.



No. 650,799. Patented May 29, I900. E. A. SANDERS.

ARCOGRAPH.

(Application filed July 10, 1899.) (No Model.)

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No. 950,799. Patented m 29, I900. E. A. SANDERS.

ABGOGRAPH.

A lication filed July 10, 1899.) (No Model.)

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PATENT OFFICE.

EDWARD A. SANDERS, OF DENVER, COLORADO.

AFRCGGRAPH.

srEoIFIoAfiIoN forming part of Letters Patent No. 650,799, dated m 29, 1900.

Application filed my 10, 1899. serial No. 723,291. (it; model.)

To aZZ whom it may concern.-

Be it known that I, EDWARD A. SANDERS, a citizen of the United States of America, residing at Denver, in the county of Arapahoe and State of Colorado, have invented certain new and useful Improvements in Arcographs; and I do declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same, reference being had to the accompanying drawings, and to the letters and figures of reference marked thereon, which form a part of this specification.

' My invention relates to improvements inarcographs or instruments for describing arcs of circles without reference to the center or without the use of a central point. My improved instrument may be made by attaching an arm provided with a graduated scale to indicate radii or diameters to an ordinary folding rule and forming an opening through the hinging center of the arms for the insertion of a pencil. A more complicated instrument may be formed for describing parallel arcs. This form of the device includes a penoil-holder automatically adjustable to maintain it in line with a radius.

The device will now be described in detail, reference being made to the accompanying drawings, in which is illustrated an embodiment thereof.

In the drawings, Figure 1 is a perspective view of my improved instrument shown in connection wit-h a device forming the bearings for the instrument at two points. This device is also adapted for extending the arc beyond the single-stroke capacity of the instrument. Fig. 2 is a fragmentary plan view of my improved device shown on alarger scale. Fig 3. is a fragmentary front view of the same. Fig. 4 is a detail.view of the auxiliary arcextension and bearing device for use in connection with the instrument. Fig. 5 is a plan view of the parallel-arc form of the device provided With the adjustable holder for the marking device, Fig. 6 is afront view of the same. Fig. 7 is a section taken through the center of the device. Fig. Sisa section taken through the hinging center of the form of the device shown in Figs. 1, 2, and 3. Figs. 9,

10, and 11 are detail views illustrating modia hollow hinge-pin 7, adapted to hold the pen oil 8. (See Fig. 8.) Connected also with the hingepin 7 is a graduated arm 9, provided with a slide 10, adapted to be locked on the arm by a set-screw 12. when in use is rigidly connected with an arm 5 or 6 by means of a suitable fastening device. is connected with the arm 5 by a spring-catch 13, attached to the arm 5 and having a pin 14, adapted to enter the opening formed in the ring of the arm 9, surrounding the hinge-pin 7. The arm 9 is normally held slightly out of line with the arm 5 in order to allow the arm 6 to assume a position in line with the arm 5 when the slide 10 is at its outerlimit of movement. The arm' 9 is graduated to indicate radii. Hence the arm may be called the radius-indicator. The radius of the are described by the instrument is regulated by the adjustment of the slide 10, the arm 6 being held against the slide. Hence the position of the slide 10 determines the angle of the arms 5 and v6, assuming that the arm 6 is in contact with the slide. The arms 5 and 6 are locked in any desired position of adjustment by means of a nut 15, screwed upon the hollow hinge-pin 7, which projects above the connected parts for the'purpose.

In the use of the instrument the radius of the arc is first determined by the adjustment of the slide 10, which is fastened by means of a set-screw 12. The arm 6 is then moved against the slide and the nut 15 tightened to lock the arms 5 and 6 in the adjusted position. Bearings for the arms 5 and 6 of the instrument are then fixed in the stationary surface, upon which the work is to be done, at arbitrary points A and B equally distant from the hinge-pin center. A pencil is also inserted in the hollew hinge-pin and allowed to protrude below sufficiently to form a line. The instrument is then moved by holding the arms 5 and 6 against the bearings fixed at the points A and B until the extremity of the arm 5 or 6 is reached, according to the di This graduated arm As shown in the drawings, the arm 9' rection of movement or until the desired length of are is described. The are thus formed may be extended by the use of the device shown in Figs. 1 and 4, which may also be used to form the bearings for the instrument in describing the original are. This device consists of two divider-arms 16 and 17, connected by a hinge-pin 18, passed through a slot 19, formed in a bisccting-arm 19. The arm 19 is further connected with the arms 16 and 17 by means of links 20, whose outer extremities are respectively pivoted to the arms 16 and 17, their inner extremities being eonneeted together by a set screw 21, passing through the slot of the arm 19. A curved arm 22 is also attached to the arm 17 and passes through a guide-strap 16, attached to the arm 16. A set-screw 16, engaging a threaded opening formed in the strap, is arranged to bear against the arm 22 and lock the divider-arms in any desired position of adjustment. The outer extremities of the arms 16 and 17 are suitably shaped to form bearings for the members 5 and 6 of the instrument. In using this bisccting device the extremities of the arms 16 and 17 are adjusted to engage the arms 5 and 6 at the points A and B. The set-screw 16 is then adjusted to lock the divider-arms in the desired position.

The instrument is then moved by holding the arms 5 and 6 against the fixed bearing extremities of the arms 16 and 17 until the extremity of one of the members 5 6 reaches the bearing extremity of the adjustable arm 16 or 17, as the case may be. The set-screw 21 is then loosened sufficiently to allow the bisccting-arm 19 to move to bring its point 19 to the line of the are. The point 19 and the bearing extremities O and D will then for1n three points to be employed in extending the are. The bisccting dividers are then moved to bring the point 19 to one extremity of the are already described, one of the bearing-pointsC D being in the are and the other projecting beyond the arc extremity. It is evident that by moving the arc-describing instrument to bring its arms in engagement with the bearing extremities C and D at the points A and 13 the are may be extended by moving the instrument as before, the arm 19 being drawn back out of the way and the set-screw 21 fastened as before.

The instrument shown in Figs. 5, 6, and 7 for drawing parallel arcs will now be described. Two arms 23 and 21 are provided with anglecxtremities 23 and 2t, connected by a hinge-pin 25. Between the angle-arms 23 and 24: there is a space 26 left to permit the use of a pencil 27, inserted in a horizontal holder 28, held by a sleeve 29, provided with a set-screw 30.

the other form of the device. This arm 31 has two angle extremities 31 and 31, arranged to conform to the corresponding another form of construction.

A graduated radius-indi-' cator 31, provided with a slide 32, held inplaee by aset-screw 33, is also employed and performs the same function as the arm 9 in i gle extremities of the arms 23 and 24. The part 31 engages alocking device 23, mounted on the arm 23. The device 23 performs the same f u notion as the part 13 in the other form of construction. Directly above the arms 23 and 21 are two slotted auxiliary arms 34: and 35, also connected with the hinge-pin 25, upon which they are adapted to turn freely. These auxiliary arms are connected with a slotted bar 36 by links 37 and 38, whose outer extremities are respectively pivoted to the two arms, while their inner extremities are connected together by a screw or small bolt 39, to which is applied a thumb-nut. This bolt 39 passes through a slot formed in the bar 36. Upon each of the arms 3t 35 is adj ustably mounted a bar 40, which is connected to the arm by means of a small bolt 41, passing through slots formed in the connected parts. In using the device the arms 23 and 21 are regulated by the adjustment of the slide 32, and the auxiliary arms 34 and 35 are arranged parallel to the arms and 2& underneath them, the pivot-bolts 41 being adjusted to occupy a position directly above the marks A and B on the arms 23 and 24:, said marks being equally distant from the hingecenter, as explained in describing the other form of construction. The arms 31 and 35 are then secured in the adjusted position by tightening the bolt 39. The slot-ted bars 40 are then turned on their pivoted bolts to oecupy positions forming angles E with the bars 3t and 35 and the arms 23 and 24, the angles E being equal to the interior angle H, formed by the arms 31 and 35 and the arms 23 and 21. The bars 10 are provided with depending flanges 40, adapted to engage the bearing-points C and D of the divider-arms, as the instrument is moved. As heretofore stated, this form of the instrument is adapted for use in forming parallel arcs. In describing the first are the bars 40 are not employed, and consequently are adjusted to conform to the position of the arms 34; and 35. In this case the pencil-point would be originally 10- eatcd at the angles II. (See Fig. 5.) The bearing-points O and D of the divider-arms are then adjusted to engage the arms 23 and 2-1 at the arbitrary but predetermined points A and B. The instrument is then used as heretofore described when explaining the Having drawn the first are, the instrument is brought back to its original position and the pencil'27 adjusted to occupy a position beyond the exterior angle of the arms 23 and 24, its movement depending upon the required distance or space between the arcs. The bars 40 are then adjusted to cause the angle E to equal the angle H, as heretofore explained, when the instrument is moved as before; but in this case the depending flange of the bar 40 engages the bearing 0 or D, as the case may be, and turns the arms 34: and 35 and the pencilsupporting bar 36 sufficiently to maintain'said bar constantly in line with a radius of the are.

Fig. 9 illustrates adovetail connection between the arm 5 and an extension-arm 5. Fig. 10 shows an extension-arm 5, hinged at J and adapted to fold after the manner of the ordinary rule. The entire instrument may be folded to occupy but little space. The angle-indicator arm9 may be detached or folded without detaching, as may be desired. It the locking device 13 (shown in Fig. 8) is employed, it is raised sufficiently to release the pin 14: from the arm 9, after which the latter may be turned to engage one of the other arms when in the folded position.

In the form of construction shown in Fig. 11 a divider-arm 16 is provided with a hollow auxiliary arm K, having a segment-arm M adj ustably connected with the arm 16 by means of a set-screw O, the segment-arm being arranged to slide in a metal strap underneath. WVithin the hollow arm K is inserted an auxiliary sliding arm K, Which-is locked in place by a set-screw K Both ends of the part K are open, and by loosening the set-screw K the part K may be made to project beyond the extremity of the part K. In using this form of the device the original arc is first described, as heretofore explained, and the arm 19 adjusted to bring its extremity to the line of the arc. The divider instrument is then moved to bring the point of the arm 19 at each extremity of the arc in succession, marks being then made to determine the radius of the are for the purpose of forming a parallel arc.

The arms K (each divider-arm being similarly equipped) are then adjusted to conform to the position of the radius-lines asdetermined by the arm 19. The arms K are then moved outwardly beyond the original arc the desired distance and locked in place. The extremities of these arms K then form the bearings for the arcograph instrument in describing the parallel arc.

Having thus described my invention, what I claim isl. The combination of two arms pivotally connected together and provided with a mark-. ing device at the pivotal center, a radius-indicator comprising a graduated arm projecting from the pivotal center of the pivoted arms and provided with a stop adapted to engage one of the pivoted arms, and two fixed bearings arranged to engage the arms at points equally distant from the pivotal center, whereby as the instrument is moved an arc is formed, as described.

2. The combination of two arms pivoted together, a radius-indicator comprising a grad-' uated arm projecting from the pivotal center of the first-named arms and provided with an adjustable stop adapted to engage one of the pivoted arms, a marking device pivotally mounted on the instrument, and means for automatically adjusting said device to maintain it in line with a radius in forming parallel arcs.

3. The combination of two arms pivotally connected together, a radius-indicator attached to the instrument, two auxiliary arms pivoted at the same center, a slotted bar also pivoted at the common center and constructed to hold a marking device, links connecting the marker-bar with the auxiliary arms by means of a device passing through the slotof the marker-bar,and a bar adj ustably mounted on an auxiliary arm.

4. The combination of an arcograph coin prising two pivoted arms, a marking device located at the pivotal cen ter,and a radius-indica= tor,and a device comprising two divider-arms pivotally connected, a slotted bisecting-arm, through which the pivot of the divider-arms passes, and links connecting the divider-arms with the bisecting-arm. by means of a fastening device passing through the link extremities and the slot of the bisecting-arm, the outer extremities of the dividerarms being fashionedto form beari n gs for the arms of the arcograph.

In testimony whereof I affix my signature in presence of two witnesses.

EDWARD A. SANDERS.

Witnesses:

A. J. OBRIEN, NELLIE G. DANIELS. 

